Two-stage hydroforming process



7, 1956 E. ARUNDALE ET AL 2,758,062

TWO-STAGE HYDROF'ORIVIING PROCESS Filed Sept. 4, 1951 2 Sheets-Sheet l I I I l I I I I I sacoma IZEAQTIQM STAGE FHLST IzEAdTlON 5TAGE g Era-Lag Grundale d2) CLbb r-rza E55} M Q 55 7, 1956 E. ARUNDALE ET AL TWO-STAGE HYDROFORMING PROCESS Filed Sept. 4, 1951 2 Sheets-Sheet 2 N mm :5 rav ant cxS Clttarneg m umkm qorruru 0060mm w o 34.55 muE mz 2:4 (1500 F0 duiuouou i 05 35m 2955a Ps 0mm omX amamuio nr k w 232C249 United States Patent TWO-STAGE HYDROFORMlN G PROCESS Erving Arundale, Westfield, Walter R. F. Guyer, Roselle, and John P.Thorn, Elizabeth, N. J., assignors to Esso Research and Engineering Company, a corporation of Delaware Application September 4, 1951, Serial No. 244,997

20 Claims. (Cl. 196-50) The present invention pertains to a process for im proving hydrocarbon fractions and particularly to a method of hydroforming fractions boiling within the motor fuel range in order to produce high yields of high anti-knock gasoline.

Increases in the compression ratio of internal combustion engines have placed greater demands upon gasoline type motor fuels for efficient, knock-free operation in such engines. These demands are being met by providing improved motor fuel base stocks and by the use of the anti-knock additives such as tetraethyl lead. Hydroforrming appears to be the most promising method for upgrading motor fuel or naphtha fractions to provide improved motor fuel base stocks because of its superior yield-octane number relationship and because hydroformed naphthas possess greater stability and give less engine deposits than thermally reformed naphthas.

Hydroforming is a catalytic reforming operation in which hydrocarbon fractions boiling Within the motor fuel or naphtha range are contacted with solid catalyst particles in the presence of hydrogen at elevated temperatures and pressures whereby the hydrocarbon fraction is increased in aromaticity and in which operation there is ordinarily no net consumption of hydrogen. Hydroforming operations are usually carried out in the presence of hydrogen or hydrogen-rich recycle gas at temperatures of 7501150 F. in the pressure range. of from about 50 to 1000 lbs. per sq. inch and in contact with such catalysts as molybdenum oxide, chromium oxide or, in general, oxides and sulfides of metals of groups IV, V, VI and VIII of the periodic system of elements alone or generally supported on a base or spacing agent such as alumina, precipitated alumina or zinc aluminate spinel.

It has also been proposed to reform or hydroform naphthas or gasoline fractions by subjecting them to the action of certain platinumor palladium-containing catalysts at temperatures of 600 to about 950 F. and at pressures of from atmospheric to about 1000 lbs. per sq. inch at hourly liquid space velocities of from about 0.1 to about v./v./hr., in the presence of from about 0.5 to about mols of hydrogen per mol of feed. Catalysts for this purpose comprise about 0.2 to about 2.0 wt. per cent of platinum or palladium upon commercial alumina or upon a dry cracking catalyst such as silicaalumina, silica-magnesia or the like. Another catalyst of this type is prepared by precipitating alumina from aluminum chloride, commingling about 0.1 to about 3.0 wt. per cent of hydrogen fluoride therewith, adding hydrogen sulfide to a chloroplatinic acid solution, commingling the resultant reaction mixture with the fluoridecontaining alumina, drying and heating the resultant composite. Hydroforming in the presence of such platinum or palladium-containing catalysts possesses the. dis.- advantage of offering a low octane number ceiling of about 85-90 (Research) when operated non-regeneratively or at pressures above about 500 lbs. per sq. inch or of providing a serious problem in maintaining catalyst activity if conducted at pressures below 500, preferably at about 200 lbs. per sq. inch since carbon deposition is appreciable at the lower pressures and removal of carbonaceous deposits by combustion with an oxygen-containing gas causes an appreciable loss in catalyst activity.

It has also been proposed to treat gasoline or motor fuel fractions of inferior knock rating in several stages with different catalysts and/or under different reaction conditions in order to effect greater improvements in the motor fuels. This field has been the subject of intensive investigation since there is still a demand for improved catalysts and/or techniques for upgrading naphtha or other lower boiling hydrocarbon fractions to form even greater amounts of higher octane number gasolines.

It is the object of this invention to provide an improved method for treating or upgrading naphthas or other lower boiling petroleum fractions.

It is also the object of this invention to provide the art witha method whereby petroleum naphthas may be up graded with high yield-octane number relationships.

It is a further object of this invention to provide an improved method for upgrading hydrocarbon fractions boiling within the naphtha range in a two stage operation..

These and other objects will appear more clearly from thedetailed specification and claims which follow.

It has nowbeen found that petroleum fractions boiling within the motor fuel or naphtha range can be upgraded with a high yield-octane relationship and with a low carbon and gas formation by treatment under reforming conditions in a two-stage process, in the first stage with a platinum or palladium catalyst at pressures of from 50 to 1000 lbs. per sq. inch, at temperatures of about 600 to 950 F. in the presence of hydrogen or hydrogen-rich recycle gas and then in a second stage with a group VI metal oxide hydroforming catalyst supported on alumina or zinc aluminate spinel at pressures of from 0 to 250 lbs. per sq. inch gauge at temperatures of from 900 to 1030 F. in the presence of hydrogen or hydrogenric'h recycle gas. This combination of process steps possesses substantial advantages since it not only permits one to obtain thev advantages of non-regenerative reforming, but it also permits the attainment of high octane number levels and a substantial increase in plant capacity. By utilizing a platinum on alumina catalyst in the first stage which is free from fluorine and substantially free (containing less than 5-6 Wt. per cent) of silica it is possible to prevent or minimize hydrocracking at the same time effect a conversion of the C5 and Cs ring naphthenes to aromatics and thereby render the naphtha particularly suitable for treatment. in the second stage with group VI metal oxide hydroforming catalysts under such conditions as to convert parafilnic constituents to high octane components. by isomerization, cracking, hydrocracking, dehydrogenation or aromatization. By conducting the reforming in the first stage with platinum or palladiumcontaining catalysts at pressures of from about 500 to 750 lbs. per sq. inch at temperatures of about 800950 F. in the presence of hydrogen or hydrogen-rich recycle gas it is possible to operate this stage non-regeneratively. This first stage can also be operated at pressures below about 500 lbs. per sq. inch non-regeneratively or substantially non-regeneratively by limiting the temperature and/or the time of contact. It is preferred to operate the first reforming stage non-regeneratively but if carbon deposition. should occur in the first reforming stage it is preferred toremove the deposits by treatment with hydrogen or hydrogen-rich recycle gas at reaction conditions or higher and to resort to combustion of the deposits by treatment with an oxygen-containing gas only after the catalyst has become appreciably deactivated through the accumulation of carbon deposits that are not removable with hydrogen. It is also possible to produce high yields of aromatic hydrocarbons from light naphthas by such a two-step process.

Reference is made to the accompanying drawings illustrating flow diagrams of two processes in accordance with the present invention. Referring to Fig. l, a hydrocarbon feed stock such as a light or heavy naphtha is supplied to the reactor system through inlet line 1. The feed stock is preheated in heater or furnace 2 and discharged into the first reaction stage 3. Hydrogen, or hydrogenrich recycle gas supplied through line 4 is also passed through heater 2 and thence into the first reaction stage 3.

The naphtha feed and the hydrogen-containing gas is contacted in first reaction stage 3 with a platinum or palladium on alumina catalyst. This catalyst should contain from about 0.2 to about 1.0 wt. per cent of platinum or 0.5 to 2.0 wt. per cent palladium and may be prepared by compositing platinum or palladium with alumina gel or with an activated alumina of commerce. If it is desired to avoid or minimize hydrocracking in the first reaction stage the catalyst should be free from fluorine ions and its content of silica should be low, or below about 6 wt. per cent. The feed stock is retained in the first reaction stage for a period sufficient to effect a substantial conversion of the C5 and Cs ring naphthenes in the feed stock into aromatics.

The reaction products from the first reaction stage are conducted through cooler 5 into separator 6. The C5 and lower boiling products are taken overhead from separator 6 through line 7 and then passed in whole or in part through cooler 8 and thence through line 9 into separator 10 wherein the C4 and C5 products are separated from the lighter products. The C4 and C5 products are conducted via line 11 to gasoline blending or storage.

The Cs+ hydrocarbons are withdrawn from separator 6 and conducted via line 12 through a pressure reducing valve, if desired, and thence into the second reaction stage 13. The hydrogen and C1-C3 hydrocarbons removed overhead from separator 10 may be passed in whole or in part through line 14 into second reaction stage 13. That portion of the hydrogen and C1C3 hydrocarbons not conducted through line 14 to the second reaction stage 13 is conducted through line 15 into line 4 for recycling to the first reaction stage. The C6+ hydrocarbon material in line 12 and the hydrogen and C1-C3 hydrocarbon material in line 14 can be passed through a heater or furnace prior to introducing the same into the second reaction stage.

The C6+ hydrocarbons supplied through line 12 and the gaseous materials supplied through line 14 pass through the second reaction stage 13 where they contact a group VI metal oxide such as molybdenum oxide or chromium oxide preferably on a support such as activated alumina or zinc aluminate spinel. The second reaction stage is operated at pressures of from 0 to 250 lbs. per sq. inch gauge and at temperatures of from 900 to 1030 F. The reactants are maintained in the second reaction stage until a substantial conversion of the paraffinic constituents to aromatics has been etfected.

The reaction products from the second reaction stage 13 are withdrawn through line 16 and passed to fractionating tower 17. Normally gaseous products such as hydrogen and C1-C hydrocarbons are taken overhead from the fractionator through line 18 and recycled in the system by passage through recycle gas line 4. Excess amounts of recycle gas may be withdrawn from the system through outlet line 19. Liquid product is withdrawn through line 20 and passed to gasoline blending or storage.

Contact of the hydrocarbon feed stock with the catalyst in the two reaction stages may be eflected in either a fixed or in a moving or fluidized bed. Contactin the two stages may be the same or different. Since little or no regeneration is necessary in the first reaction stage it may advantageously be operated in a fixed bed. In any event it should be understood that while the reaction stages are indicated as single vessels they may comprise more than one vessel, for example it may be advantageous to provide in moving bed or fluidized solids systems a reactor vessel and a separate regeneration vessel and if desired a third vessel for reconditioning catalyst after regeneration and prior to placing the catalyst back into operation. Also it may be desired to provide several reactors and to operate them in series with or without reheating between reactors or in parallel in order to obtain the degree of conversion and/or conversion capacity.

Fig. 2 illustrates a flow plan of a particularly advantageous manner of carrying out the process in accordance with the present invention. In Fig. 2 naphtha feed supplied through line 31 is passed through heating coils 32 in furnace 33. Hydrogen or hydrogen-rich recycle gas is supplied through line 34 and passed through heating coil 35 in furnace 33. If desired, at least a portion of the recycle gas may be combined with the naphtha feed before passage through the heating coils in furnace 33. The preheated feed naphtha and the heated hydrogen-rich gas are combined and passed through line 36 into the first reaction stage 37 which is a fixed bed reactor charged with a platinumor palladium-containing catalyst. The first reactor stage is operated non-regeneratively, either by operating at pressures above 500 lbs. per sq. inch and with adequate hydrogen partial pressure or by operating at pressures below 500 lbs. per sq. inch and limiting the temperature and/or the time of contact in order to avoid carbon deposition. In this reactor system it is desirable from an engineering standpoint to operate the first reforming stage at a pressure which is only sufficiently above the pressure in the second or fluid hydroforming stage to take care of normal pressure drop through the system. Contact of the naphtha with the platinum or palladium catalyst in the first reaction stage is generally continued until the naphthenes in the feed stock are converted to aromatics.

The reaction products from the first reaction stage are conducted from reactor 37 via line 38 to heating coils 39 in reheat furnace 40 whereupon the reheated reaction products are discharged via line 41 into the base of vessel 42 in which the second reaction stage is conducted. The second reaction stage is carried out in a fluidized solids reactor system, the vessel 42 being charged with a finely divided catalyst comprising a suitable group VI metal oxide such as molybdenum oxide, chromium oxide or tungsten oxide upon a suitable support such as activated alumina or zinc aluminate spinel. The catalyst particles are, for the most part between 200 and 400 mesh in size or about 0200 microns in diameter with a major proportion between 20 and microns.

The reaction product vapors supplied through line 41 to reactor vessel 42 are passed through the vessel 42 at a superficial velocity of about 0.2 to 0.9 ft. per second at reactor conditions depending upon the pressure. For example, the velocity should be below 0.6 ft. per second in the pressure range of 200-250 lbs. per sq. inch. The velocity should be suflicient to maintain a dense, turbulent, liquid simulating bed 43 of solids and vapors having a level 44 with a dilute phase suspension of vapors and solids 45 thereabove. Introduction of the reaction products from line 41 into reactor 42 is preferably effected below a perforated distribution plate or grid arranged at the bottom of the reactor in order to insure uniform distribution of the reactants over the entire cross section of the reactor vessel. If desired, the reactor 44 may also vapors and catalyst.

Catalyst is continuously withdrawn directly from the dense bed 43 and conveyed via line 46 into regenerator with one or more vertically spaced ports or orifices for passage of catalyst into said vertical conduit means are also provided for introducing steam or an inert gas such as nitrogen, flue gas, or mixtures thereof in order to displace, strip off or desorb hydrogen, hydrocarbon reactants or reaction products flowing into the withdrawal conduit along with the catalyst. The stripping gas is passed upwardly through the withdrawal conduit countercurrent to the downfiowing catalyst and is discharged from the upper end of the withdrawal conduit into the dilute or disperse phase 45. The superficial velocity of the stripping gas through the withdrawal conduit should be equal to or higher than the superficial velocity of the vapors and gases passing upwardly through the reactor 18.

The velocity of the regeneration gas passing upwardly through the regenerator 47 is controlled to maintain a lower dense, highly turbulent bed 49 of catalyst particles and regeneration gas having a definite level 50 and a dilute or disperse catalyst phase 51 in the upper part of the regenerator. To accomplish this, the superficial velocity of the gas passing through the regenerator vessel 47 may range between 0.3 and 1.5 ft. per second, depending upon the pressure, for example at about 1.0 ft. per second at a regeneration pressure of about 200-250 lbs. per sq. inch. A valve controlled conduit 52 is provided for transferring regenerated catalyst from regenerator vessel 47 into the main reaction vessel 42. Since the catalytic metal oxide is often oxidized in the regeneration operation it is generally advisable to contact the regenerated catalyst with a hydrogen-rich gas before returning the regenerated catalyst to the hydroforming reaction stage. This can advantageously be effected in the present arrangement in the transfer line 52. If necessary to maintain control of the temperature of the catalyst during regeneration, cooling coils or the like may be provided in the regenerator vessel 47.

The gaseous products are taken overhead from the regeneration vessel, passed through cyclone separators or the like to remove the bulk of the entrained catalyst particles which are returned to the dense bed via a dip leg or the like attached to the cylone separators in known manner whereupon the regeneration gases are discharged through flue 53, or, if desired, processed to recover heat or energy therefrom and/or passed to suitable storage means for use as stripping gas when needed. A pressure control valve is provided in line 53 in order to maintain the desired pressure in the regeneration zone.

Returning to the reactor vessel 42, the reaction products are taken overhead through cyclone separators 54 or the like which remove most of the entrained catalyst from the reaction products. Separated catalyst particles are returned to the dense bed 43 via the dip leg 55 connected to the bottom of the cyclone separator. The reaction products substantially free from catalyst particles are passed via line 56 through condenser 57 where they are brought into indirect heat exchange with fresh feed for example in order to preheat the latter and to condense the normally liquid constituents of the reaction mixture. The cooled products are passed from condenser 57 via line 58 into separator 59. The liquid product is withdrawn from separator 59 via line 60 and is then passed to suitable re-run or stabilization equipment and thence to product storage or blending. The process gases, rich in hydrogen are taken overhead from separator 59 via line 61 to vent line 62 where excess process gas is removed. The remainder of the process gas is passed via compressor 63 into recycle gas line 34 for recirculation to the furnace 33 and first reaction stage 37.

The catalysts used in the first reaction stage consist essentially of platinum or palladium upon activated '76 alumina of commerce 'or upon alumina gel. The support may contain small amounts of silica, for example not more than 6 wt. per cent. In order to minimize the hydrocrackng activity of the catalyst used in the first reaction stage, the presence of silica in and also the addition of hydrogen fluoride to the support or the catalyst composite should be avoided. The platinum or palladium may be incorporated on the base by impregnating the same with a solution of awater soluble compound of the catalytic metal, treating with a precipitant such as hydrogen sulfide, heating to decompose the catalytic metal compound or reducing with hydrogen. Before placing the catalyst on stream it is advisable to further reduce the catalyst by treating the same with hydrogen or hydrogenrich gas at elevated temperatures. The catalyst should contain from 0.2 to 1.0 wt. per cent of platinum or from 0.5 to 2.0 wt. per cent of palladium.

Treatment of the hydrocarbon feed with platinumor palladium-containing catalyst in the first reaction stage is conducted at temperatures of from 600 to 950 F. preferably at 850 to 900 F. and at pressures of from 50 to 1000 lbs. per sq. inch, preferably at pressures of 500 to 750 lbs. per sq. inch. It is necessary to provide hydrogen in the reaction zone either by supplying hydrogen directly thereto or preferably by recycling process gases to the reaction zone. The hydrogen/hydrocarbon mol ratio may be from 4/1 to 6/1, preferably about 5/1 to 6/1. Under the reaction conditions there is no net consumption of hydrogen in the reaction and accordingly recycle of the process gases or the normally gaseous products should provide a sufficient hydrogen partial pressure in the reaction zone. The feed rates through the first reaction zone should be in the range of from 2 to 5 volumes of feed per volume of catalyst per hour.

Catalysts used in the second reaction stage are the oxides or sulfides of group VI metals upon suitable spacing agents such as activated alumina or upon zinc aluminate spinel. Preferred catalysts for the second reaction stage are those containing from about 8 to 15 wt. per cent molybdenum oxide upon 92 to wt. per cent of alumina or zinc aluminate spinel or those containing about 15 to 40 wt. per cent chromium oxide on 85-60 wt. per cent of activated alumina or zinc aluminate spinel. The catalyst may also contain up to about 0.752.0 wt. per cent of an oxide stabilizer or promoter such as potassia or ceria.

The treatment of the liquid reaction products from the first reaction stage in contact with the group VI metal oxide or sulfide catalyst in the second reaction stage is conducted at temperatures of from 900 to 1030 F., preferably at 900 to 950 F. for molybdena catalysts and 9901030 F. for chromium oxide-containing catalysts and at pressures of from 0 to 250 lbs. per square inch gauge, preferably at to 200 lbs. per sq. inch for molybdena catalysts and 050 lbs. per square inch for chromia-containing catalysts. Hydrogen, or recycle gas rich in hydrogen is provided in the second stage reaction zone in order to minimize carbon or coke formation and increase the liquid product yield. The space velocities in the second stage should be in the range of 0.2-4.5 vols. of feed/vol. of catalyst per hour.

EXAMPLE I Feedstock: Heavy virgin naphtha from mixed crudes boiling between 200-360 F. and possessing a Re search octane number clear of 45.

First stage conditions Catalyst: 0.5% platinum on H-41 alumina (from Aluminum Company of America-contains 5% SiOz) Temperature: 900 F.

Pressure: 700 p. s. i. g.

Liquid space velocity: 4 vols. feed/vol. catalyst/hr.

Hydrogen dilution: 5 moles Hz/mole hydrocarbon Second stage conditions Catalyst: 10% M003 on H-41 alumina Temperature: 900 F.

Pressure: 200 p. s. i. g.

Liquid space velocity: 0.25 vol. feed/vol. catalyst/hr. Hydrogen dilution: 2.5 moles Hz/mole hydrocarbon EXAMPLE II Feedstock: C6 light naphtha fraction containing cyclohexane, normal hexane and methyl cyclopentane.

First stage conditions Catalyst: 0.5% platinum on F-lO alumina (from Aluminum Company of America-of low silica content).

Temperature: 850 F.

Pressure: 600 p. s. i. g.

Liquid space velocity: 3.5 vols. feed/ vol. catalyst/hr.

Hydrogen dilution: 6 moles Hz/mole hydrocarbon Second stage conditions Catalyst: .00 parts H-41 alumina, 29 parts CrzOs, 2

parts potassia, 0.86 parts ceria.

Temperature: 1000-1010 F.

Pressure: p. s. i. g.

Liquid space velocity: 0.23-0.32

Hydrogen dilution: 2 moles Hz/mole hydrocarbon The foregoing description contains a limited number of embodiments of the present invention. It will be understood, however, that numerous variations are possible without departing from the scope of the following claims.

What is claimed is:

1. A method of hydroforming hydrocarbon fractions boiling within the motor fuel range which comprises contacting said hydrocarbons in admixture with hydrogenrich gas in a first reaction stage with a catalyst consisting of a member of the group consisting of platinum and palladium upon alumina at temperatures of 600 to 950 F. and at pressures of from 50 to 1000 lbs. per sq. inch for a period suificient to convert a substantial portion of the naphthenes in the feed stock to aromatics and contacting the reaction products from said first reaction stage with a catalyst comprising a member of the group consisting of group VI metal oxides and sulfides at temperatures of 900 to 1030 F. and at pressures of 0 to 250 lbs. per sq. inch gauge.

2. A method of hydroforming hydrocarbon fractions boiling within the motor fuel range which comprises contacting said hydrocarbons in admixture with hydrogenrich gas in a first reaction stage with a catalyst consisting of 0.2-1.0 wt. per cent platinum upon alumina at temperatures of 600 to 950 F. and at pressures of from 50 to 1000 lbs. per sq. inch for a period sufficient to convert a substantial portion of the naphthenes in the feed stock to aromatics and contacting the reaction products from said first reaction stage with a catalyst comprising a member of the group consisting of group VI metal oxides and sulfides upon a carrier at temperatures of 900 to 1030 F. and at pressures of 0 to 250 lbs. per sq. inch gauge.

3. A method of hydroforming hydrocarbon fractions boiling within the motor fuel range which comprises contacting said hydrocarbons in admixture with hydrogenrich gas in a first reaction stage with a catalyst consisting of 0.2-1.0 wt. per cent platinum upon alumina at temperatures of 600 to 950 F. and at pressures of from 50 to 1000 lbs. per sq. inch for a period sufficient to convert a substantial portion of the naphthenes in the feed stock to aromatics and contacting the reaction products from said first reaction stage with a catalyst comprising 8-15 wt. per cent of molybdenum oxide upon alumina at temperatures of 900 to 1030 F. and at pressures of 0 to 250 lbs. per sq. inch gauge.

4. A method of hydroforming hydrocarbon fractions boiling within the motor fuel range which comprises contacting said hydrocarbons in admixture with hydrogenrich gas in a first reaction stage with a catalyst consisting of 0.2-1.0 wt. per cent platinum upon alumina at temperatures of 600 to 950 F. and at pressures of from 50 to 1000 lbs. per sq. inch for a period sufficient to convert a substantial portion of the naphthenes in the feed stock to aromatics and contacting the reaction products from said first reaction stage with a catalyst comprising 8-15 wt. per cent of molybdenum oxide upon zinc aluminate spinel at temperatures of 900 to 1030 F. and at pressures of 0 to 250 lbs. per sq. inch gauge.

5. A method of hydroforming hydrocarbon fractions boiling within the motor fuel range which comprises contacting said hydrocarbons in admixture with hydrogenrich gas in a first reaction stage with a catalyst consisting of 0.2-1.0 wt. per cent platinum upon alumina at temperatures of 600 to 950 F. and at pressures of from 50 to 1000 lbs. per sq. inch for a period sufiicient to convert a substantial portion of the naphthenes in the feed stock to aromatics and contacting the reaction products from said first reaction stage with a catalyst comprising 15 to 40 wt. per cent of chromium oxide upon alumina at temperatures of 900 to 1030 F. and at pressures of 0 to 250 lbs. per sq. inch gauge.

6. A method of hydroforming hydrocarbon fractions boiling within the motor fuel range which comprises contacting said hydrocarbons in admixture with hydrogenrich gas in a first reaction stage with a catalyst consisting of 0.2-1.0 wt. per cent platinum upon alumina at temperatures of 600 to 950 F. and at pressures of from 50 to 1000 lbs. per sq. inch for a period sufficient to convert a substantial portion of the naphthenes in the feed stock to aromatics and contacting the reaction products from said first reaction stage with a catalyst comprising 15 to 40 wt. per cent of chromium oxide upon zinc aluminate spinel at temperatures of 900 to 1030 F. and at pressures of 0 to 250 lbs. per sq. inch gauge.

7. A method of hydroforming hydrocarbon fractions boiling within the motor fuel range which comprises contacting said hydrocarbons in admixture with hydrogenrich gas in a first reaction stage with a catalyst consisting of a member of the group consisting of platinum and palladium upon alumina at temperatures of 800 to 900 F. and at pressures of from 500 to 750 lbs. per sq. inch for a period sufiicient to convert a substantial portion of the naphthenes in the feed stock to aromatics and contacting the reaction products from said first reaction stage with a catalyst comprising a member of the group consisting of group VI metal oxides and sulfides at temperatures of 900 to 1030 F. and at pressures of 0 to 250 lbs. per sq. inch gauge.

8. A method of hydroforming hydrocarbon fractions boiling within the motor fuel range which comprises contacting said hydrocarbons in admixture with hydrogenrich gas in a first reaction stage with a catalyst consisting of 0.2-1.0 Wt. per cent platinum upon alumina at temperatures of 800 to 900 F. and at pressures of from 500 to 750 lbs. per sq. inch for a period sufficient to convert a substantial portion of the naphthenes in the feed stock to aromatics and contacting the reaction products from said first reaction stage with a catalyst comprising a member of the group consisting of group VI metal oxides and sulfides upon a carrier at temperatures of 900 to 1030 F. and at pressures of 0 to 250 lbs. per sq. inch gauge.

9. A method of hydroforming hydrocarbon fractions boiling within the motor fuel range which comprises contacting said hydrocarbons in admixture with hydrogenrich gas in a first reaction stage with a catalyst consisting of 0.2-1.0 Wt. per cent platinum upon alumina at temperatures of 800 to 900 F. and at pressures of from 500 to 750 lbs. per sq. inch for a period sufficient to convert a substantial portion of the naphthenes in the feed stock to aromatics and contacting the reaction products from said first reaction stage with a catalyst comprising 8-15 Wt. per cent of molybdenum oxide upon alumina at temperatures of 900 to 1030 F. and at pressures of to 250 lbs. per sq. inch gauge.

10. A method of hydroforming hydrocarbon fractions boiling within the motor fuel range which comprises contacting said hydrocarbons in admixture with hydrogenrich gas in a first reaction stage with a catalyst consisting of 0.2-l.0 wt. per cent platinum upon alumina at temperatures of 800 to 900 F. and at pressures of from 500 to 750 lbs. per sq. inch for a period sufficient to convert a substantial portion of the naphthenes in the feed stock to aromatics and contacting the reaction products from said first reaction stage with a catalyst comprising 8-15 wt. per cent of molybdenum oxide upon zinc aluminate spinel at temperatures of 900 to 1030 F. and at pressures of 0 to 250 lbs. per sq. inch gauge.

11. A method of hydroforming hydrocarbon fractions boiling within the motor fuel range which comprises contacting said hydrocarbons in admixture with hydrogenrich gas in a first reaction stage with a catalyst consisting of 0.21.0 wt. per cent platinum upon alumina at temperatures of 800 to 900 F. and at pressures of from 500 to 750 lbs. per sq. inch for a period suificient to convert a substantial portion of the naphthenes in the feed stock to aromatics and contacting the reaction products from said first reaction stage with a catalyst comprising to 40 wt. per cent of chromium oxide upon alumina at temperatures of 900 to 1030 F. and at pressures of 0 to 250 lbs. per sq. inch gauge.

12. A method of hydroforming hydrocarbon fractions boiling within the motor fuel range which comprises contacting said hydrocarbons in admixture with hydrogen-rich gas in a first reaction stage with a catalyst consisting of 0.2-1.0 wt. per cent platinum upon alumina at temperatures of 800 to 900 F. and at pressures of from 500 to 750 lbs. per sq. inch for a period suflicient to convert a substantial portion of the naphthenes in the feed stock to aromatics and contacting the reaction products from said first reaction stage with a catalyst comprising 15 to 40 wt. per cent of chromium oxide upon zinc aluminate spinel at temperatures of 900 to 1030 F. and at pressures of 0 to 250 lbs. per sq. inch gauge.

13. A method of hydroforming hydrocarbon fractions boiling Within the motor fuel range which comprises contacting said hydrocarbons in admixture with hydrogenrich gas in a first reaction stage with a fixed bed of catalyst consisting of a member of the group consisting of platinum and palladium upon alumina at temperatures of 600 to 950 F. and at pressures of from 50 to 1000 lbs. per sq. inch for a period suflicient to convert a substantial portion of the naphthenes in the feed stock to aromatics and contacting the reaction products from said first reaction stage with a dense, fluidized liquid simulating bed of finely divided catalyst comprising a member of the group consisting of group VI metal oxides and sulfides at temperatures of 900 to 1030 F. and at pressures of 0 to 250 lbs. per sq. inch gauge.

14. A method of hydroforming hydrocarbon fractions boiling within the motor fuel range which comprises contacting said hydrocarbons in admixture with hydrogenrich gas in a first reaction stage with a fixed bed of catalyst consisting of a member of the group consisting of platinum and palladium upon alumina at temperatures of 800 to 900 F. and at pressures of from 500 to 750 lbs. per sq. inch for a period sufficient to convert a substantial portion of the naphthenes in the feed stock to aromatics and contacting the reaction products from said first reaction stage with a dense, fluidized liquid simulating bed of finely divided catalyst comprising a member of the group consisting of group VI metal oxides and sulfides at temperatures of 900 to 1030 F. and at pressures of 0 to 250 lbs. per sq. inch gauge.

15. The process as defined in claim 7 in which the catalyst utilized in the first reaction stage contains less than 6 Wt. per cent silica and is essentially free of fluorine ions.

16. The process as defined in claim 8 in which the catalyst utilized in the first reaction stage contains less than 6 wt. per cent silica and is essentially free of fluorine ions.

17. The process as defined in claim 9 in which the catalyst utilized in the first reaction stage contains less than 6 Wt. per cent silica and is essentially free of fluorine IOHS.

18. The process as defined in claim 10 in which the catalyst utilized in the first reaction stage contains less than 6 wt. per cent silica and is essentially free of fluorine ions.

19. The process as defined in claim 11 in which the catalyst utilized in the first reaction stage contains less than 6 Wt. per cent silica and is essentially free of fluorine ions.

20. The process as defined in claim 12 in which the catalyst utilized in the first reaction stage contains less than 6 wt. per cent silica and is essentially free of fluorine ions. 1

References Cited in the file of this patent UNITED STATES PATENTS 2,479,110 Haensel Aug. 16, 1949 2,487,563 Sayng Nov. 8, 1949 2,522,696 Watson Sept. 19, 1950 2,556,280 Kearby June 12, 1951 2,573,149 Kassell Oct. 30, 1951 2,596,145 Grote May 13, 1952 

1. A METHOD OF HYDROFORMING HYDROCARBON FRACTIONS BOILING WITHIN THE MOTOR FUEL RANGE WHICH COMPRISES CONTACTING SAID HYDROCARBONS IN ADMIXTURE WITH HYDROGENRICH GAS IN A FIRST REACTION STAGE WITH A CATALYST CONSISTING OF A MEMBER OF THE GROUP CONSISTING OF PLATINUM AND PALLADIUM UPON ALUMINA AT TEMPERATURES OF 600 TO 950* F. AND AT PRESSURES OF FROM 50 TO 1000 LBS. PER SQ. INCH FOR A PERIOD SUFFICIENT TO CONVERT A SUBSTANTIAL PORTION OF THE NAPHTHENES IN THE FEED STOCK TO AROMATICS AND CONTACTING THE REACTION PRODUCTS FROM SAID FIRST REACTION STAGE WITH A CATALYST COMPRISING A MEMBER OF THE GROUP CONSISTING OF GROUP V1 METAL OXIDES AND SULFIDES AT TEMPERATURES OF 900* TO 1030* F. AND AT PRESSURES OF 0 TO 250 LBS. PER SQ. INCH GAUGE.
 13. A METHOD OF HYDROFORMING HYDROCARBON FRACTIONS BOILING WIHIN THE MOTOR FUEL RANGE WHICH COMPRISES CONTACTING SAID HYDROCARBONS IN ADMIXTURE WITH HYDROGENRICH GAS IN A FIRST REACTION STAGE WITH A FIXED BED OF CATALYST CONSISTING OF A MEMBER OF THE GROUP CONSISTING OF PLATINUM AND PALLADIUM UPON ALUMINA AT TEMPERATURES OF 600* TO 950* F. AND A PRESSURES OF ROM 50 TO 1000 LBS. PER SQ. INCH FOR A PERIOD SUFFICIENT TO CONVERT A SUBSTANTIAL PORTION OF THE NAPHTHENES IN THE FEED STOCK TO AROMATICS AND CONTACTING THE REACTION PRODUCTS FROM SAID FIRST REACTION STAGE WITH A DENSE, FLUIDIZED LIQUID SIMULATING BED OF FINELY DIVIDED CATALYST COMPRISING A MEMBER OF THE GROUP CONSISTING OF GROUP VI METAL OXIDES AND SULFIDES AT TEMPERATURES OF 900* F. AND AT PRESSURES OF 0 TO 250 LBS. PER SQ. INCH GAUGE. 